The design of low-cost and durable electrocatalysts with high catalytic performance of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial for the development of sustainable energy technologies. NiFe-layered double hydroxide (NiFe-LDH) is a promising electrocatalyst for OER, but the poor ORR activity limits its large-scale application as a bifunctional electrocatalyst in energy storage and conversion devices. The rational design of hierarchical nanohybrids is an effective strategy to construct bifunctional OER/ORR electrocatalysts. Herein, a high-performance OER/ORR bifunctional non-noble metal electrocatalyst (NiFe-LDH/CoNC-PIN) was projected. The Co-doped carbon frameworks with porous interconnecting networks (CoNC-PIN) is prepared by pyrolysis of ZIF-8/67 via a salt template strategy, followed by the uniform in situ growth of ultrathin NiFe-LDH nanosheets on CoNC-PIN to construct the hierarchical NiFe-LDH/CoNC-PIN hybrid. The molten NaCl template in pyrolysis activates the surface of ZIF-8/67 and connects them into porous carbon networks to improve the surface area, porosity and electronic conductivity of catalysts. Due to the efficient electron transfer and strong coupling between CoNC-PIN and NiFe-LDH, the NiFe-LDH/CoNC-PIN exhibits a small OER overpotential of 249 mV at 10 mA/cm2, a low Tafel slope of 27.7 mV/dec, an ORR half-wave potential of 0.80 V, and excellent durability and structural stability. This strategy provides a novel insight to fabricate advanced OER/ORR bifunctional non-noble metal electrocatalysts.

The role of defects in multifunctional materials and defect engineering are fascinating to scientific community. To understand the role of oxygen vacancies in photoluminescence (PL) and oxygen reduction reaction (ORR), thoria samples were prepared with Eu3+ doping and Nb5+ codoping. The positron annihilation lifetime spectroscpy (PALS) showed the increase in the oxygen vacancies in thoria upon trivalent Eu3+ doping and their removal upon codoping with Nb5+. This is in concordance with increase in nearest oxygen neighbours to Eu3+ and Th4+ upon Nb5+ codoping as revealed by Extended X-ray Absorption Fine Structure (EXAFS). Oxygen vacancy removal on Nb5+ codoping manifested in restoration of symmetry around Eu3+ and enhanced photoluminescence (PL) intensities giving very bright red emission while the oxygen vacancy rich thoria samples aided the electrochemical ORR. The studies showed that the concentration of the oxygen vacancies can be tuned upon the judicious choice and concentration of the aliovalent dopant and codopant depending on the envisaged functionality of the material.

Current methods for tuning the taper angle of photosensitive polyimide (PSPI) often require additional equipment or materials, and has limited achievable angle tuning range while maintaining resolution. To overcome these limitations, a positive tone chemically amplified photosensitive polyimide (p-CA-PSPI) was prepared from tert-butylcarbonate-protected polyimide (t-Boc-PI), photoacid generator (PAG), other additives, and solvent. By optimizing the protection ratios of t-Boc-PI resins, the p-CA-PSPI achieved a high film retention rate and wide processing window. The photo-patterning conditions were able to manipulate the sidewall profile and taper angle within the range of 11–53°, maintaining a resolution of 3 μm for patterns with taper angles higher than 28° at 1.5 μm film thickness, by controlling the acid diffusion. The thermally cured polyimide films demonstrated excellent mechanical properties, including a tensile strength of 95.7 MPa, tensile modulus of 2.9 GPa, and elongation at breakage of 24.2%, high thermal stability with a glass transition temperature of 343 °C, decomposition temperature of 409 °C, and good chemical resistance. This novel taper angle tuning method has the potential to optimize the internal stress of semiconductor devices and advance the development of display devices, MEMs, and multifunctional electronics that require a single package containing multiple or unique taper profiles.

Recently, two-dimensional ferroelectrics with spontaneous electric polarization have attracted growing interest for application in gas sensors and other electronic devices. This study proposes an in-plane polarization-induced sensor based on the α-In2Se3 ferroelectric material with reversible gas capture or release. A comprehensive quantum mechanical analysis on the characteristics of the device is presented by employing density functional theory calculations, ab initio molecular dynamic simulations, and the non-equilibrium Green's function formalism. The ferroelectricity of α-In2Se3 results in different surface polarizations, leading to different adsorption behaviors on surfaces with opposite polarizations. Based on the adsorption energy, charge transfer, and recovery time, the negatively polarized surface is better suited for gas capture than the positively polarized surface. Consequently, by applying a vertical electric field, which changes the out-of-plane polarization, reversible capture or release of NH3 and NO2 molecules can be achieved. However, applying vertical electric fields in transistor-based gas sensors is rather challenging. Meanwhile, the unique interlocking feature of electric dipoles in α-In2Se3 monolayer can be used to control gas adsorption or desorption by an in-plane bias voltage (electric field). The sensitivities of the positive and negative surfaces to the NH3 molecule are 107.6% and 11.3%, respectively, when an appropriate in-plane bias voltage is applied. The proposed sensor that allows manipulating the out-of-plane polarization by an in-plane bias is of special importance and opens up a new pathway for sensing applications.

Zeolites are commonly used for selective CO2 adsorption from biogas and flue gas. One of the biggest challenges for zeolites in this application is the presence of water vapour in the raw gas streams. While zeolites with low Si/Al ratio typically display high CO2 adsorption, they are hydrophilic and H2O competes for adsorption on the active sites. On the other hand, zeolites with high Si/Al ratio are hydrophobic, but display lower CO2 adsorption capacities. In order to overcome this limitation and to combine the high CO2 adsorption capacity of low Si/Al zeolites and the hydrophobicity of high Si/Al zeolites into a single material, we designed and synthesized novel core-shell zeolitic beads comprising a ZSM-5 core and a Silicalite-1 shell. Two different strategies were employed to synthesize these macroscopic core-shell beads. In both approaches, the initial step was the synthesis of binderless ZSM-5 beads with hierarchical porosity using resin beads as hard template. In the first strategy, a shell of Silicalite-1 was synthesized on the external surface of the calcined ZSM-5 beads, yielding Sil-ZSM-A core-shell beads (0.84 ± 0.12 mm). In the second strategy, the Silicalite-1 shell was synthesized without first removing the polymeric template from the ZSM-5 beads, resulting in core-shell composite beads that after calcination yielded Sil-ZSM-B core-shell beads (0.73 ± 0.14 mm). Characterization by SEM, XRD, XRF, ICP-AES and N2 physisorption indicated that both Sil-ZSM-A and Sil-ZSM-B beads displayed the desired zeolitic core-shell structure with hierarchical porosity. Both core-shell beads showed the anticipated increase in hydrophobicity. The most promising results were obtained with Sil-ZSM-A beads, which displayed a 40% decrease in H2O adsorption capacity at 20% relative humidity (RH) and a 28% decrease at max RH compared to the parent ZSM-5 beads. At the same time, their CO2 adsorption capacity (1.94 mmol/g at 1 bar) decreased only slightly compared to the parent ZSM-5 beads (2.13 mmol/g at 1 bar). These results indicate that these core-shell beads present the desired combination of the high CO2 adsorption capacity of the ZSM-5 core with the hydrophobicity of the Silicalite-1 shell. This is a promising feature for application in the adsorption of CO2 from water-containing streams.

Bismuth tungstate (Bi2WO6)-based photocatalytic materials have become a research hotspot in photocatalytic energy conversion and environmental remediation due to their low-toxicity, abundant, ease of preparation, chemical stability as well as excellent structural, electrical and optical properties. However, the main disadvantage of pure semiconductors, including Bi2WO6, is associated with the rapid recombination of photogenerated charge carriers, which leads to low activity. As one of the approaches to solve this challenge, the preparation of heterojunctions based on Bi2WO6 has been proven as the most efficient, reliable and promising strategy. This critical review explores the use of Bi2WO6-based heterojunction photocatalysts with a focus on Z-scheme and S-scheme composites for environmental remediation, including air purification and wastewater treatment. Moreover, the challenges and opportunities are considered to further insight into developing new photocatalytic materials with their future commercialization on an industrial scale. Some new approaches for further improving Bi2WO6-based photocatalysts, such as optimization of preparation method, hetero- and homo-substitution of A-site or B-site (atomic regulation) and the use of support matrix, are highlighted.

Metal organic frameworks (MOFs) are developing as promising catalysts for oxygen evolution reactions. A bimetallic electrocatalyst MOF using Ni and Cu as metal sources and 1,4-benzene dicarboxylic acid as a linker has been synthesized and evaluated for oxygen evolution reaction. Compared to monometallic MOFs, bimetallic MOFs participate more actively in electrocatalysis due to the higher abundance of active sites, local crystallinity, and lower long-range disorder. When utilized as oxygen evolution catalysts, Ni–Cu MOFs have a low overpotential of 340 mV at 10 mA/cm2 and a low Tafel slope of 65 mV/dec. The study paves the way for the development of highly efficient catalysts for water splitting applications.

All-inorganic perovskite quantum dots (QDs) as high-quality materials for backlight display are still limited by their own low stability. Herein, the crystallization of CsPbBr3 (CPB) QDs in a glass matrix was promoted by modifying the glass network structure with alkaline earth metals (Mg, Ca, Sr, Ba). What's more, a washing-heat treatment cycle strategy was used to optimize the best-modified sample (CPB–Mg). Among them, CPB-12Mg (add 12% MgO) showed a high photoluminescence quantum yield (PLQY = 62%) after the cycling process. More surprisingly, the six-step washing-heat treated-sample (CPB–12Mg-6) showed excellent stability. When CPB-12Mg-6 was irradiated for 240 h at 60°C, 90% relative humidity (RH), and 880 W/m2 blue light power (60°C, 90% RH, 880 W/m2), the original 90% fluorescence emission could still be maintained. Subsequently, a series of CPB-12Mg-6/CsPbBr1.5I1.5@PS light conversion films were prepared by the master batch blending method. The backlight conversion film for liquid crystal display (LCD) achieves a wide color gamut that covers 126% of the NTSC 1953 and 93.6% of the Rec.2020 standard. This innovative washing-heat treatment cycle strategy provides a new idea for improving the stability of perovskite quantum dots.

Polydiacetylenes (PDAs) are color-responsive materials that have shown potential as colorimetric sensors for detecting various classes of analytes. However, the utilization of PDAs for sensing ultraviolet-B light (UVB) is rare. This contribution introduces a facile method for enhancing the UVB-responsive property of PDAs by incorporating zinc oxide (ZnO) quantum dots (QDs). We explore the size effects of ZnO QDs/nanoparticles and diacetylene (DA) monomers on the sensitivity of the resultant nanocomposites to UVB light. Interestingly, the sensitivity of nanocomposites to UV light with different wavelengths can be controlled by adjusting the size of ZnO nanoparticles. We have found that the incorporation of ZnO QDs with diameters ranging from 2.2 to 3.8 nm drastically increases the sensitivity to UVB light. In addition, fine-tuning of the UVB sensitivity can be achieved by varying alkyl chain lengths of the DA monomers. The colorimetric response of nanocomposites to specific UVB regions can be obtained by adjusting the band gap of ZnO QDs. This property allows their utilization as colorimetric sensors for detecting UVB doses in sunlight and other sources. Colorimetric UVB sensors can be fabricated in different forms including smart ink sensors, free-standing flexible sensors, paper-based sensors, and hydrogel-based sensors.

A facile, safe, and environmentally friendly preparation method is described for the synthesis of AlFx(OH)3-x by the activation of γ-Al2O3 using HCFO-1233zd(E) under various temperatures. Comprehensive characterization techniques including XRD, XPS, N2 sorption, SEM, TEM, 27Al MAS NMR, FTIR, and py-IR were employed, revealing that at lower temperatures such as 275 °C and 300 °C, the synthesis yielded AlF(OH)2, while at higher temperatures like 350 °C and 375 °C, pyrochlore AlF1.5(OH)1.5 and metastable hexagonal tungsten bronze-type (HTB) β-AlF3 were formed, with α-AlF3 detected at 325 °C. Notably, a significant quantity of AlF(OH)2 can be obtained at 325 °C within a specific time frame. This amorphous phase exhibits weak Lewis acid sites and a lower acid density, rendering it significantly more effective in the isomerization of HCFO-1233zd(E) compared to strong Lewis acid catalysts such as AlF1.5(OH)1.5 and β-AlF3, which could promote coke formation, leading to catalyst deactivation. Moreover, due to its limited further fluorination at 290 °C, the optimal catalyst exhibits prolonged lifespan and high efficiency in HCFO-1233zd(E) isomerization.

Ammonium perchlorate (AP) is commonly used as an oxidant in composite solid propellants (CSPs). The thermal behavior of AP has a significant impact on CSP combustion. This study investigates the thermal behavior of Al-AP-Fe2O3 and Al@AP-Fe2O3 particles, which were produced using a recrystallization method, under various pressures. The ability of Fe2O3 to regulate the decomposition rate of AP and the reasons for the reduced ignition delay under enhanced Fe2O3 catalysis are also explored by using density functional theory (DFT) calculations. The results indicate that Fe2O3 with a large catalytic contact area has a strong ability to regulate the decomposition rate of AP. The decreasing trend of the temperature difference between low- and high-temperature decomposition peaks belonging to the Al@AP-Fe2O3 (32 °C (0.1 MPa) → 19 °C (1.0 MPa) → 14 °C (4.0 MPa)) is weaker than that of the Al-AP-Fe2O3 (60 °C (0.1 MPa) → 25 °C (1.0 MPa) → 0 °C (4.0 MPa)) under various pressures. Additionally, the low activation energy of ∗NH4ClO4 → ∗NH3 + ∗H (∗O3b) + ∗ClO4 (300 °C: 0.207 eV) is the main reason for the initial decomposition of AP to accelerate and the ignition delay to be reduced under the more adequate α-Fe2O3 catalysis. Furthermore, the catalysis of α-Fe2O3 with a large contact area can further facilitate or control the oxidation of NH3 under various pressures or temperatures, influencing the decomposition of AP and enabling its regulation. This study therefore highlights the importance of understanding the catalytic properties of Fe2O3 for improving the performance of CSPs and optimizing their combustion behavior.

Non-invasive sweat detectors can monitor the glucose level of diabetes in a painless way. However, most detectors need to collect enough sweat through external exercise or active stimulation, which increases the inconvenience of the user and reduces the applicable population. In this study, we propose an ultra-sensitive biomimetic glucose detector to detect the sweat produced by thermoregulation without additional exercise and stimulation. Inspired by the predator process of sponge in the sea, the sensing material of MXene (Ti3C2Tx) @CeO2 hydrogels employed the “laminae-trestle-laminae” (L-T-L) structure of sponge to adsorb and transport glucose molecules in sweat. CeO2 grafted onto the MXene surface can detect glucose by the catalytic activity of CeO2. The glucose detector with an ultra-low limit of detection (LOD = 0.004 μM), excellent sensitivity (801.27 μA⋅μM−1⋅cm−2), and a broad linear detection range (LDR = 0.01–2.5 μM) can satisfy detection requirements in human sweat after dilution. In real applications, the detector can detect glucose in the sweat of diabetic patients for five consecutive days and detect the glucose content in the daily drinks of patients. Our findings demonstrate the high potential of sponge-inspired MXene@CeO2 glucose detector for routine medical testing.

Rational design and construction of multiphase composite with specifical structure is an effective strategy to fabricate high-performance supercapacitor electrode materials. Herein, the hierarchical CoMoO3@Co9S8/Ni3S2 core-shell arrays are constructed by preparing Co9S8/Ni3S2 core with ion-exchange reaction and fabricating CoMoO3 shell through in situ transformation behavior. Thanks to the special heterostructures core-shell structure, the synergistic effect between multiple components, and the driving action of S-vacancies, hierarchical CoMoO3@Co9S8/Ni3S2 core-shell arrays exhibit battery-type features and deliver a great area specific capacity of 8.14 C cm−2 at current density of 5 mA cm−2. In addition, when assembled into a hybrid supercapacitor with capacitive-type electrode, the device achieves high energy density of 0.33 mWh cm−2 at the power density of 5.66 mW cm−2 and displays long-term durability with capacity retention of 93.7% and high Coulombic efficiency of 95.01% after 6000 cycles.

Remedied during processing and service life, and then controlled ecologically, are ideal behaviors for polymers. Antioxidants and prooxidants always play their respective roles during the programming of their actions, and the oxygen-containing groups are non-controllable during oxidative stress. This work demonstrates an eco-friendly remedial strategy for polyester-based thermoplastic polyurethanes (TPUs). Upon the thermal-oxidative stressing, Fe(III) ions were released from the 2,2-bisferrocenylpropane doped in TPUs, polyester chains underwent β-scission, and iron-catalyzed oxidation directed new end groups to carboxylates. Ferroxane was progressively constructed by interaction between Fex3+Oy (2x > 3y) and external carboxylates. Consequently, the metallo-supramolecular networks were constructed to mitigate the mechanical degradation. Compared to virgin TPU, the sample containing only 1.0 wt% 2,2-bisferrocenylpropane, with 10-day thermal-oxidative stressing showed distinctly outperforming tensile strength (42.7 ± 1.9 MPa), breaking elongation (984 ± 61%), and Young's modulus (32.0 ± 1.6 MPa). The study would be interesting for preventing failure, lessening waste, and diminishing toxicity of the polymer, which is consistent with sustainable development.

We have investigated the host/guest molecular interactions and the H-bonding clustering in the H2O/HKUST-1 system. In-situ Fourier transform infrared spectroscopy was the experimental technique used to gather information at the molecular level. Measurements collected under sorption equilibrium conditions and in a dynamic regime were interpreted with the aid of a detailed QM vibrational analysis of the host/guest adduct and of a series of H2O clusters. The local arrangement of the adduct formed by H2O and the coordinatively unsaturated sites was characterized in terms of structure and interaction energy, and signatures for this adduct were predicted by theory in the ν(OH) range and experimentally confirmed. Within the metal organic framework nanocavities, six-membered water clusters having specific conformations were found to be the prevailing species. Cyclic trimers were also identified, their stabilization being ascribed to nanoconfining effects. The analysis of the δ(HOH) range elucidated the nature of the complex band shape and confirmed the results obtained in the ν(OH) interval. Low-temperature measurements allowed us to exclude the crystallization of the water clusters in the nanocavities.

Cardiac troponin I (cTnI) is a specific biomarker of myocardial damage. Several techniques have been reported for cTnI detection, which is based on immunoaffinity, aptamers, and molecular imprinting polymers. Using computational methods, we introduced a novel chemical receptor for cTnI, named tetrabromophenol blue (TBPB), which interacted with cTnI selectivity in the presence of human serum albumin (HSA), cardiac troponin C (cTnC) and C reactive protein (CRP). Employing TBPB as a chemical receptor, a novel electrochemical sensor was constructed for the electrochemical sensing of cTnI. A glassy carbon electrode surface was modified with layered double hydroxide nanostructures (LDHNS) and TBPB. The modified electrode showed electrocatalytic activity toward ascorbic acid (AA) in a phosphate buffer solution (pH 7.4). The results revealed that using AA as a signal enhancer for cTnI detection could be a good idea. The linear range (50.00–3.50 × 105 pM) and detection limit (2.77 pM) were calculated using differential pulse voltammetry to measure cTnI at the TBPB/meso-Fe/CoLDHNS/GCE in a pH 7.40 buffer solution containing 1 mM of AA. Firstly, based on our docking studies, TBPB showed a very low tendency towards HSA, cTnC, and CRP. Additionally, the selectivity of TBPB/meso-Fe/CoLDHNS/GCE for cTnI was studied electrochemically in the presence of HSA, cTnC, and CRP.

Because of its toxicity and ubiquity in the environment, Bisphenol A (BA) is a prominent endocrine-disrupting compound widely employed in polycarbonate plastics and epoxy resins. BA causes severe health risks for humans. To resolve this, we crafted a selective electrochemical sensor through an efficient electrocatalyst, reduced graphene oxide (RGO) wrapped barium oxide/molybdenum oxide (BMO) nanorod, developed via the hydrothermal method. BMO/RGO nanocomposite was characterized and employed for electrocatalytic performance. BMO displays admirable selectivity, stability, and sensitivity for the determination of BA. Differential pulse voltammetry (DPV) was used for the electrocatalytic study of BMO/RGO nanocomposite for detecting BA. Our proposed sensor displayed a linear enhancement of current when the concentration of BA was increased from 0.01 to 723 μM with a limit of detection (LOD) of 0.004 μM. Furthermore, the proposed sensor is a tool for the rapid and sensitive detection of environmental samples.

Flexible piezoelectric nanogenerators (PENGs) are promising candidates for clean energy harvesting and powering electronics, especially for low-power modules. In this study, a PENG has been fabricated by incorporating functionalized mono-/few-layered hexagonal boron nitride nanosheets (F-hBNNS) in a polyvinylidene fluoride (PVDF) polymeric matrix. The synthesized 2D nanosheets are well characterized using different spectroscopic and microscopic methods. The analysis showed successful exfoliation of hBN, which indicated less than three layers of hBN after exfoliation and sulfonated and carboxylated functionalization on the surface. Also, the piezoresponse force microscopy (PFM) tests revealed a 3 times higher piezoelectric coefficient for F-hBNNS compared to that of the non-functionalized hBN with the same number of layers. The synthesized F-hBNNS with piezo-flexoelectric properties boosted the energy harvesting performance of the electrospun PVDF-based fibrous mats 5.5 times. The open-circuit output voltage test showed 23 V at 4 Hz with a power density of 1.93 μW/cm2 at a resistance loading of 16 MΩ in a simple finger tapping. The fabricated PENGs showed no decline in voltage output over 1000 cycles of bending-unbending of a robotic finger. It is proposed that the enhanced performance is due to (i) the synergistic effects of the flexoelectric and piezoelectric properties of synthesized F-hBNNS in the PVDF matrix and (ii) the manipulation of the crystalline structure of the PVDF chains, which is increased to 90% β-phase crystallinity with 49.03% total degree of crystallinity. This study shows the compatibility of the fabricated PENGs with the human body's biomechanics for being used as an efficient energy source for wearable devices with low power consumption.

Ordered mesoporous silicas are important technological materials in catalysis, sorption and separation science, however new architectures are desired to improve in-pore accessibility. Here we report the first synthesis of an ordered macroporous KIT-6, obtained by optimizing the ratios of Pluronic P123: sodium dodecyl sulfate cosurfactants, and a 400 nm polystyrene nanosphere macropore template. The macroporous KIT-6 possesses 370 nm macropores in a face-centered cubic arrangement, surrounded by a silica framework comprised of cubic Ia3¯d three-dimensional, intertwined 5 nm mesopore channels. Propylsulfonic acid (PrSO3H) functionalization affords a macroporous KIT-6 solid acid catalyst whose hierarchical pore network permits rapid diffusion and esterification of fatty acids, conferring a five-fold enhancement for palmitic acid esterification compared with a conventional mesoporous PrSO3H/KIT-6, and 33% rate enhancement vs. an ordered macroporous PrSO3H/SBA-15.

Abstract not available